Electronic paper can be a great way to get the news, complete with streaming video (mockup photo Univ. of Cincinnati).

By Walter SalmPhoenix, AZ — Which is the best display for our data, entertainment, office work, movies on the go? The three major technologies — LED, backlighted LCD, and plasma all have their pros and cons. Now another player is anxious to get into the mix — electronic paper or electrofluidic display (EF) — a technology that has some serious advantages, not the least of which is near-zero power operation. The display is like paper — flexible, rollable, foldable, and provides superior optical contrast in direct sunlight. Further, it can offer panel integration with PV power sources.

The electronic paper has a spectacular introduction at January?s Consumer Electronics Show in Las Vegas. But in spite of all of the hype, there's still a lot of work to be done before EF becomes a truly viable, marketable product. Chief player right now is Gamma Dynamics Corp. in Phoenix in partnership with the University of Cincinnati (Ohio).

This new entry into the race for full-color electronic paper can potentially provide better than 85 percent "white-state reflectance," a performance level required for consumers to accept reflective display applications such as e-books, cell-phones and signage.

Better Technology"If you compare this technology to what's been developed previously, there's no comparison," says developer Jason Heikenfeld, assistant professor of electrical engineering in UC's College of Engineering. "We're ahead by a wide margin in critical categories such as brightness, color saturation and video speed."

This work, which has been underway for several years, has just been published in the paper "Electrofluidic displays using Young-Laplace transposition of brilliant pigment dispersions." Lead author Heikenfeld explains the primary advantage of the approach. "The ultimate reflective display would simply place the best colorants used by the printing industry directly beneath the front viewing substrate of a display," he says. "In our EFD pixels, we are able to hide or reveal colored pigment in a manner that is optically superior to the techniques used in electrowetting, electrophoretic and electrochromic displays."

Because the optically active layer can be less than 15 microns thick, project partners at PolymerVision see strong potential for rollable displays. The product offerings could be extremely diverse, including electronic windows and tunable color casings on portable electronics.

"This takes the Amazon Kindle, for example, which is black and white, and could make it full color," Heikenfeld says. "So now you could take it from a niche product to a mainstream product."

Monochrome Comes FirstThe first tiny pigment droplets that pop up through the paper-bright white background of Gamma e-paper are black and white, and all of the initial development efforts are directed at making this manufacturable and reliable. But mono is not an inherent limitation; it's just the first step. Color is on its own development track and Gamma has said that it will have something to show publicly in about a year.

The appearance of the display is very much like paper with print on it. As such, its first applications may well be for e-books — better, brighter more readable paper, and cheaper, without glare or washouts.

The displays can be manufactured as active (up to video rates) or bistable (zero power except to change), they can be flexible or rigid, monochrome or color, paper-like or transparent.

The initial work at Gamma has focused on what it takes to turn pixels on and off, then what it takes to do it faster. The next major step is how to accomplish grey scales, which are a plus for monochrome, but a necessity for anything other than primitive "paint box" color.Grey scale work is following several paths,primarily involving either spatial or temporal finesse. Color work can't get serious until grey scale is solved.

While electrofluidic display technology sounds like a single solution, it actually describes a fairly broad cluster of achievable displays, each with its own attributes. Despite the university backgrounds of many members of the development team, the pure science is not their goal. The immediate priority is to be able to get into very small volume prototype production that will allow them to more quickly refine the electronics, fluidics and legibility alternatives of the best possible displays that are consistent with good production yields. While these prototypes will all remain in house, the end of the summer of 2012 could bring some stunning new results.